Specially in say foggy conditions and little bit distance. At which point you won't clearly maybe differentiate individual elements and more like that's the rear and "block of light in middle, left and right". At which point it all little blending one might infact be under impression "the light intensity lowered at the rear, huh, not braking then, did they have they parking break dragging they released or something.... ohhhjj shuiiiiiit no it is braking hard".
My two cents from here north of Europe and land of snow, rain, fog and occasional white out conditions.
Well it could also be a lever or a switch.